1. Field
Example embodiments relate to high electron mobility transistors and/or methods of manufacturing high electron mobility transistors, and more particularly, to high electron mobility transistors capable of flowing electric current forward and backward and/or methods of manufacturing high electron mobility transistors capable of flowing electric current forward and backward.
2. Description of the Related Art
In a power conversion system, an efficiency of the entire system may depend upon an efficiency of a semiconductor switching device. A power metal oxide semiconductor field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT) using silicon has been mainly used as a switching device; however, increasing efficiency of the switching device may be limited to due to the characteristics of the silicon itself.
To overcome the limitations of silicon material, research into a high electron mobility transistor (HEMT) is being actively conducted.
A HEMT may include semiconductor layers having different electrical polarization characteristics from each other. A semiconductor layer having a relatively large polarizability in the HEMT may cause two-dimensional electron gas (2DEG) in other semiconductor layers that are hetero-bonded with the semiconductor layer. The 2DEG may be used as a channel between a drain electrode and a source electrode, and an electric current flowing in the channel may be controlled by a bias voltage applied to a gate electrode.
On the other hand, in a field effect semiconductor switching device such as the HEMT, an electric potential of the drain electrode may be lower than that of the source electrode, and accordingly, a reverse direction voltage may be applied to the field effect semiconductor switching device. To address this problem, a freewheeling diode may be connected to the field effect semiconductor device in parallel.
However, as described above, if the freewheeling diode is connected to the semiconductor device as an additional device, an additional process for fabricating the freewheeling diode may be necessary. Moreover, a size of the semiconductor switching device may increase, and fabrication costs may also increase.